U.S. patent number 10,369,533 [Application Number 15/021,567] was granted by the patent office on 2019-08-06 for dosing and mixing arrangement for use in exhaust aftertreatment.
This patent grant is currently assigned to Donaldson Company, Inc.. The grantee listed for this patent is Donaldson Company, Inc.. Invention is credited to Bruce Bernard Hoppenstedt, Matthew S. Whitten.
United States Patent |
10,369,533 |
Whitten , et al. |
August 6, 2019 |
Dosing and mixing arrangement for use in exhaust aftertreatment
Abstract
Dosing and mixing exhaust gas includes directing exhaust gas
towards a periphery of a mixing tube that is configured to direct
the exhaust gas to flow around and through the mixing tube to
effectively mix and dose exhaust gas within a relatively small
area. Some mixing tubes include a slotted region and a non-slotted
region. Some mixing tubes include a louvered region and a
non-louvered region. Some mixing tubes are offset within a mixing
region of a housing.
Inventors: |
Whitten; Matthew S. (St. Paul,
MN), Hoppenstedt; Bruce Bernard (Scandia, MN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Donaldson Company, Inc. |
Minneapolis |
MN |
US |
|
|
Assignee: |
Donaldson Company, Inc.
(Minneapolis, MN)
|
Family
ID: |
51627361 |
Appl.
No.: |
15/021,567 |
Filed: |
September 12, 2014 |
PCT
Filed: |
September 12, 2014 |
PCT No.: |
PCT/US2014/055404 |
371(c)(1),(2),(4) Date: |
March 11, 2016 |
PCT
Pub. No.: |
WO2015/038897 |
PCT
Pub. Date: |
March 19, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170282135 A1 |
Oct 5, 2017 |
|
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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61877749 |
Sep 13, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01F
3/04049 (20130101); B01F 5/0057 (20130101); F01N
3/20 (20130101); B01F 3/04 (20130101); B01F
5/00 (20130101); B01F 5/0451 (20130101); B01F
5/04 (20130101); F01N 1/088 (20130101); F01N
13/009 (20140601); F01N 2240/20 (20130101); B01F
2005/0091 (20130101); F01N 2610/02 (20130101); F01N
3/2892 (20130101); B01F 2005/0011 (20130101); F01N
3/106 (20130101); F01N 3/2066 (20130101); F01N
3/035 (20130101); F01N 2470/18 (20130101) |
Current International
Class: |
F02K
1/38 (20060101); B01F 5/00 (20060101); B01F
3/04 (20060101); F01N 3/20 (20060101); B01F
5/04 (20060101); F01N 3/28 (20060101); F01N
1/08 (20060101); F01N 3/035 (20060101); F01N
13/00 (20100101); F01N 3/10 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2111916 |
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Oct 2009 |
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EP |
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2128398 |
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Dec 2009 |
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EP |
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Other References
International Search Report for PCT/US2014/055404, dated Nov. 21,
2014. cited by applicant.
|
Primary Examiner: Bogue; Jesse S
Attorney, Agent or Firm: Merchant & Gould P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application is a US National Stage application of PCT
International Patent application No. PCT/US2014/055404, filed Sep.
12, 2014, which claims priority to U.S. Provisional Patent
Application Ser. No. 61/877,749 filed on Sep. 13, 2013, which
applications are incorporated herein by reference. To the extent
appropriate, a claim of priority is made to each of the above
applications.
Claims
What is claimed is:
1. A mixing tube arrangement for swirling exhaust gases, the mixing
tube arrangement comprising: a tube body having a longitudinal axis
extending along an interior passage from a first end of the tube
body to a second end of the tube body, the tube body defining a
slotted region and a non-slotted region, the slotted region
defining a plurality of slots, the slotted region extending over a
first continuous circumferential distance of the tube body and the
non-slotted region extending over a second continuous
circumferential distance of the tube body, the second
circumferential distance being less than the first circumferential
distance, and the second continuous circumferential distance being
larger than a circumferential distance of any portion of the tube
body extending between two adjacent slots at the slotted region,
and the width of each slot being less than half of the second
continuous circumferential distance; and a plurality of louvers
disposed at the slots.
2. The mixing tube arrangement of claim 1, further comprising a
doser disposed at the first end of the tube body, the doser being
configured to dispense a reactant into exhaust flowing through the
interior passage of the tube body.
3. The mixing tube arrangement of claim 1, wherein the slotted
region extends along less than a full length of the tube body.
4. The mixing tube arrangement of claim 1, wherein a ratio of an
axial length of each slot to a diameter of the tube body is 1.5 to
2.
5. The mixing tube arrangement of claim 4, wherein the ratio of the
axial length of each slot to the diameter of the tube body is
1.75.
6. The mixing tube arrangement of claim 1, wherein the louvers
extend away from the tube body at an angle of 45.degree..
7. The mixing tube arrangement of claim 1, wherein the slotted
region extends along 210.degree. to 330.degree. of a circumference
of the tube body.
8. The mixing tube arrangement of claim 7, wherein the slotted
region extends along 270.degree. of the circumference of the tube
body.
9. The mixing tube arrangement of claim 1, wherein a ratio of a
circumferential width of each slot to a diameter of the tube body
is 0.05 to 0.15.
10. The mixing tube arrangement of claim 9, wherein the ratio of
the circumferential width of each slot to the diameter of the tube
body is 0.1.
11. The mixing tube arrangement of claim 1, wherein a diameter of
the tube body is 5 inches, a circumferential width of each slot is
0.45 inches and a length of each slot is 8 inches.
12. The mixing tube arrangement of claim 11, wherein the slots
define 45% of an area of the slotted region.
13. A dosing and mixing arrangement comprising: a housing defining
an inlet having an inlet axis, a mixing region, and an outlet
having an outlet axis, the outlet axis being generally orthogonal
to the inlet axis; a mixing tube arrangement disposed within the
mixing region of the housing, the mixing tube arrangement including
a tube body defining an interior passage that extends along the
outlet axis, the tube body having a circumferential surface
extending across the inlet axis, the circumferential surface having
a continuous louvered region and a continuous non-louvered region,
the louvered region defining a plurality of louvers extending
outwardly from a circumferential surface of the tube body, the
non-louvered region being free of louvers, the non-louvered region
having a circumferential width that is larger than a
circumferential width of a portion of the tube body extending
between two adjacent louvers at the louvered region, the tube body
also defining a plurality of slots that extend through the
circumferential surface of the tube body, each louver being
associated with at least one slot, each slot having a common width
defined along a circumference of the tube body.
14. The dosing and mixing arrangement of claim 13, wherein the
mixing tube arrangement touches an interior portion of the
housing.
15. The dosing and mixing arrangement of claim 14, wherein a distal
end of one of the louvers contacts the interior portion of the
housing.
16. The dosing and mixing arrangement of claim 13, wherein the
mixing tube arrangement is offset within the housing to define a
high pressure zone and a flow zone.
17. The dosing and mixing arrangement of claim 13, wherein the
mixing tube arrangement defines the outlet of the housing.
18. The dosing and mixing arrangement of claim 13, wherein at least
a portion of the louvered region faces towards the inlet.
19. The dosing and mixing arrangement of claim 13, wherein at least
a portion of the non-louvered region faces away from the inlet.
20. The dosing and mixing arrangement of claim 13, wherein an area
of the louvered region extends over 270.degree. of the
circumferential surface of the tube body.
21. The mixing tube arrangement of claim 1, wherein the slotted
region extends over a majority of an axial length of the mixing
tube.
Description
BACKGROUND
Vehicles equipped with internal combustion engines (e.g., diesel
engines) typically include exhaust systems that have aftertreatment
components such as selective catalytic reduction (SCR) catalyst
devices, lean NOx catalyst devices, or lean NOx trap devices to
reduce the amount of undesirable gases, such as nitrogen oxides
(NOx) in the exhaust. In order for these types of aftertreatment
devices to work properly, a doser injects reactants, such as urea,
ammonia, or hydrocarbons, into the exhaust gas. As the exhaust gas
and reactants flow through the aftertreatment device, the exhaust
gas and reactants convert the undesirable gases, such as NOx, into
more acceptable gases, such as nitrogen and water. However, the
efficiency of the aftertreatment system depends upon how evenly the
reactants are mixed with the exhaust gases. Therefore, there is a
need for a flow device that provides a uniform mixture of exhaust
gases and reactants.
SCR exhaust treatment devices focus on the reduction of nitrogen
oxides. In SCR systems, a reductant (e.g., aqueous urea solution)
is dosed into the exhaust stream. The reductant reacts with
nitrogen oxides while passing through an SCR substrate to reduce
the nitrogen oxides to nitrogen and water. When aqueous urea is
used as a reductant, the aqueous urea is converted to ammonia which
in turn reacts with the nitrogen oxides to covert the nitrogen
oxides to nitrogen and water. Dosing, mixing and evaporation of
aqueous urea solution can be challenging because the urea and
by-products from the reaction of urea to ammonia can form deposits
on the surfaces of the aftertreatment devices. Such deposits can
accumulate over time and partially block or otherwise disturb
effective exhaust flow through the aftertreatment device.
SUMMARY
An aspect of the present disclosure relates to a method for dosing
and mixing exhaust gas in exhaust aftertreatment. Another aspect of
the present disclosure relates to a dosing and mixing unit for use
in exhaust aftertreatment. More specifically, the present
disclosure relates to a dosing and mixing unit including a mixing
tube configured to direct exhaust gas flow to flow around and
through the mixing tube to effectively mix and dose exhaust gas
within a relatively small area.
In accordance with some aspects, the mixing tube includes a slotted
region and a non-slotted region. In examples, the slotted region
extends over a majority of a circumference of the mixing tube. In
examples, the slotted region extends over a majority of an axial
length of the mixing tube. In examples, a circumferential width of
the non-slotted region is substantially larger than a
circumferential width of a gap between slots of the slotted
region.
In accordance with some aspects, the mixing tube includes a
louvered region and a non-louvered region. The louvered region
extends over a majority of a circumference of the mixing tube. In
examples, the louvered region extends over a majority of an axial
length of the mixing tube. In examples, a circumferential width of
the non-slotted region is substantially larger than a
circumferential width of a gap between louvers of the louvered
region.
In accordance with some aspects, the mixing tube is offset within a
mixing region of a housing. For example, the mixing tube can be
located closer to one wall of the housing than to an opposite wall
of the housing.
A variety of additional aspects will be set forth in the
description that follows. These aspects can relate to individual
features and to combinations of features. It is to be understood
that both the foregoing general description and the following
detailed description are exemplary and explanatory only and are not
restrictive of the broad concepts upon which the embodiments
disclosed herein are based.
DRAWINGS
The accompanying drawings, which are incorporated in and constitute
a part of the description, illustrate several aspects of the
present disclosure. A brief description of the drawings is as
follows:
FIG. 1 is a schematic representation of a first exhaust treatment
system incorporating a doser and mixing unit in accordance with the
principles of the present disclosure;
FIG. 2 is a schematic representation of a second exhaust treatment
system incorporating a doser and mixing unit in accordance with the
principles of the present disclosure;
FIG. 3 is a schematic representation of a third exhaust treatment
system incorporating a doser and mixing unit in accordance with the
principles of the present disclosure;
FIG. 4 is a perspective view of an example doser and mixing unit
configured in accordance with the principles of the present
disclosure;
FIG. 5 is a cross-sectional view of the doser and mixing unit of
FIG. 4 taken along the plane 5 of FIG. 4;
FIG. 6 is a cross-sectional view of the doser and mixing unit of
FIG. 4 taken along the housing axis C shown in FIG. 5;
FIG. 7 is a perspective view of an example mixing tube arrangement
suitable for use with the doser and mixing unit of FIG. 4;
FIG. 8 is a side elevational view of the mixing tube arrangement of
FIG. 7; and
FIG. 9 is an end view of the mixing tube arrangement of FIG. 7.
DETAILED DESCRIPTION
Reference will now be made in detail to the exemplary aspects of
the present disclosure that are illustrated in the accompanying
drawings. Wherever possible, the same reference numbers will be
used throughout the drawings to refer to the same or like
structure.
FIGS. 1-3 illustrate various exhaust flow treatment systems
including an internal combustion engine 201 and a dosing and mixing
unit 207. FIG. 1 shows a first treatment system 200 in which a pipe
202 carries exhaust from the engine 201 to the dosing and mixing
unit 207, where reactant (e.g., aqueous urea) is injected (at 206)
into the exhaust stream and mixed with the exhaust stream. A pipe
208 carries the exhaust stream containing the reactant from the
dosing and mixing unit 207 to a treatment substrate (e.g., an SCR
device) 209 where nitrogen oxides are reduced to nitrogen and
water.
FIG. 2 shows an alternative system 220 that is substantially
similar to the system 200 of FIG. 1 except that a separate
aftertreatment substrate 203 (e.g., a Diesel Particulate Filter
(DPF) or Diesel Oxidation Catalyst (DOC)) is positioned between the
engine 201 and the dosing and mixing unit 207. The pipe 202 carries
the exhaust stream from the engine 201 to the aftertreatment
substrate 203 and another pipe 204 carries the treated exhaust
stream to the dosing and mixing device 207. FIG. 3 shows an
alternative system 240 that is substantially similar to the system
220 of FIG. 2 except that the aftertreatment device 203 is combined
with the dosing and mixing unit 207 as a single unit 205.
A selective catalytic reduction (SCR) catalyst device is typically
used in an exhaust system to remove undesirable gases such as
nitrogen oxides (NOx) from the vehicle's emissions. SCR's are
capable of converting NOx to nitrogen and oxygen in an oxygen rich
environment with the assistance of reactants such as urea or
ammonia, which are injected into the exhaust stream upstream of the
SCR through a doser. In alternative implementations, other
aftertreatment devices such as lean NOx catalyst devices or lean
NOx traps could be used in place of the SCR catalyst device, and
other reactants (e.g., hydrocarbons) can be dispensed by the
doser.
A lean NOx catalyst device is also capable of converting NOx to
nitrogen and oxygen. In contrast to SCR's, lean NOx catalysts use
hydrocarbons as reducing agents/reactants for conversion of NOx to
nitrogen and oxygen. The hydrocarbon is injected into the exhaust
stream upstream of the lean NOx catalyst. At the lean NOx catalyst,
the NOx reacts with the injected hydrocarbons with the assistance
of a catalyst to reduce the NOx to nitrogen and oxygen. While the
exhaust treatment systems 200, 220, 240 are described as including
an SCR, it will be understood that the scope of the present
disclosure is not limited to an SCR as there are various catalyst
devices (a lean NOx catalyst substrate, a SCR substrate, a SCRF
substrate (i.e., a SCR coating on a particulate filter), and a NOx
trap substrate) that can be used in accordance with the principles
of the present disclosure.
The lean NOx traps use a material such as barium oxide to absorb
NOx during lean burn operating conditions. During fuel rich
operations, the NOx is desorbed and converted to nitrogen and
oxygen by reaction with hydrocarbons in the presence of catalysts
(precious metals) within the traps.
FIGS. 4-6 show a dosing and mixing unit 100 suitable for use as
dosing and mixing unit 207 in the treatment systems disclosed
above. The dosing and mixing unit 100 includes a housing 102 having
an interior 104 accessible through an inlet 101 and an outlet 109.
A mixing tube arrangement 110 is disposed within the interior 104
(see FIGS. 5 and 6). With reference to the treatment systems 200,
220, 240, the inlet 101 receives exhaust flow from the engine 201
(or the treatment substrate 203) and the outlet 109 leads to the
SCR 209. In certain implementations, the treatment substrate 203
also can be disposed within the housing 102 to form the combined
unit 205 of FIG. 3.
As shown in FIG. 5, the housing 102 extends from a first end 105 to
a second end 106 along a housing axis C. In an example, the housing
axis C (i.e., an inlet axis) defines a flow axis for the inlet 101.
The housing 102 also extends from a third end 107 to a fourth end
108 along a longitudinal axis L (i.e., outlet axis) of the mixing
tube arrangement 110. In certain implementations, the housing axis
C is not centered between the third and fourth ends 107, 108. In an
example, the housing axis C is located closer to the third end 107.
In certain implementations, the longitudinal axis L is not centered
between the first and second ends 105, 106. In an example, the
longitudinal axis L is located closer to the second end 106.
In an example, the longitudinal axis L defines a flow axis for the
outlet 109. In certain implementations, the second end 106 is
closed. In certain implementations, the second end 106 is curved to
define a contoured interior surface 122. In an example, the second
end 106 defines half of a cylindrical shape. In certain
implementations, the third end 107 defines a port 140 at which a
doser can be coupled (see FIG. 4). In other implementations, a
doser can be disposed within the housing 102 at the third end
107.
As shown in FIG. 6, the housing 102 also has a first side 123 and a
second side 124 that extend between the first and second ends 105,
106 and between the third and fourth ends 107, 108. In certain
implementations, the first and second sides 123, 124 are closed.
The closed second end 106 contours between the first and second
sides 123, 124 (see FIG. 6). As shown in FIG. 6, the interior 104
of the housing 102 defines an inlet region 120 having a first
volume and a mixing region 121 having a second, larger volume. The
mixing region 121 extends from the inlet region 120 to the second
end 106 of the housing 102. The mixing tube arrangement 110 is
disposed within the mixing region 121.
As shown in FIG. 6, exhaust gas G flows from the inlet 101 towards
the second end 106 of the housing 102. As the exhaust gas G
approaches the mixing tube arrangement 110, some of the exhaust gas
G begins to swirl within the housing interior 104. The mixing tube
arrangement 110 causes the exhaust gas G to swirl about the
longitudinal axis L (FIG. 5) of the mixing tube arrangement 110. In
certain implementations, the mixing tube arrangement 110 defines
slots 113 (which will be discussed in more detail below) through
which the exhaust gas G enters the mixing tube arrangement 110. In
certain implementations, the mixing tube arrangement 110 includes
louvers 114 (which will be discussed in more detail below) that
direct the exhaust gas G through the slots 113 in a swirling flow
along a first circumferential direction D1 (FIG. 6).
A doser (or doser port) is disposed at one end of the mixing tube
arrangement 110 (see FIG. 5). The doser is configured to inject
reactant (e.g., aqueous urea) into the swirling flow G. Examples of
the reactant include, but are not limited to, ammonia, urea, or a
hydrocarbon. The doser can be aligned with the longitudinal axis L
of the mixing tube arrangement 110 so as to generate a spray
pattern concentric about the axis L. In other embodiments, the
reactant doser may be positioned upstream from the mixing tube
arrangement 110 or downstream from the mixing tube arrangement 110.
The opposite end of the mixing tube arrangement 110 defines the
outlet 109 of the unit 100. Accordingly, the reactant and exhaust
gas mixture is directed in a swirling flow out through the outlet
109 of the housing 102.
In other implementations, the dosing and mixing unit 100 can be
used to mix hydrocarbons with the exhaust to reactivate a diesel
particulate filter (DPF). In such implementations, the reactant
doser injects hydrocarbons into the gas flow within the mixing tube
arrangement 110. The mixed gas leaves the mixing tube arrangement
110 and is directed to a downstream diesel oxidation catalyst (DOC)
at which the hydrocarbons ignite to heat the exhaust gas. The
heated gas is then directed to the DPF to burn particulate clogging
the filter.
In some implementations, the mixing tube arrangement 110 is offset
within the mixing region 121. For example, the mixing tube
arrangement 110 can be disposed so that a cross-sectional area of
the annulus is decreasing as the flow travels along a perimeter of
the mixing tube arrangement 110. In the example shown, the mixing
tube arrangement is located closer to the second side 124 than to
the first side 123. In other implementations, however, the mixing
tube arrangement 110 can be located closer to the first side 123.
In some implementations, offsetting the mixing tube arrangement 110
guides the exhaust flow in the first circumferential direction D1.
In some implementations, offsetting the mixing tube arrangement 110
inhibits exhaust gases G from flowing in an opposite
circumferential direction.
For example, offsetting the mixing tube arrangement may create a
high pressure zone 125 and a flow zone 126. The high pressure zone
125 is defined where the mixing tube arrangement 110 approaches the
closest side (e.g., the second side 124). As the exterior surface
of the mixing tube arrangement 110 approaches the housing side 124,
less flow can pass between the mixing tube arrangement 110 and the
side 124. Accordingly, the flow pressure builds and directs the
exhaust gases away from the high pressure zone 125. The flow zone
126 is defined along the portions of the mixing tube 110 that are
spaced farther from the wall (e.g., side wall 123, interior surface
122), thereby enabling flow between the mixing tube arrangement 110
and the wall.
In certain implementations, a portion of the mixing tube
arrangement 110 contacts the closest side wall (e.g., side wall
124). For example, a distal end of a louver 114 (see FIGS. 7-9) of
the mixing tube arrangement 110 may contact (see 128 of FIG. 6) the
closest side wall 124. In such implementations, the contact 128
between the mixing tube arrangement 110 and the wall 124 further
inhibits (or blocks) flow in the opposite circumferential
direction.
FIGS. 7-9 illustrate one example mixing tube arrangement 110
including a tube body 111 defining a hollow interior 112. The tube
body 111 has a length L1. The tube body 111 has a slotted region
115 extending over a portion of the tube body 111. One or more
slots 113 are defined through a circumferential surface of the tube
body 111 at the slotted region 115. The slots 113 lead from an
exterior of the tube body 111 into the interior 112 of the tube
body 111. In some implementations, the slots 113 include
axially-extending slots 113. In certain implementations, the tube
body 111 defines no more than one axial slot 113 per radial
position along the circumference of the tube body 111. In certain
implementations, the slotted region 115 includes portions of the
tube body 111 extending circumferentially between the slots 113 in
the slotted region 115.
In some implementations, the slotted region 115 defines multiple
slots 113. In certain implementations, the slotted region 115
defines between five slots 113 and twenty-five slots 113. In
certain implementations, the slotted region 115 defines between ten
slots 113 and twenty slots 113. In an example, the slotted region
115 defines about fifteen slots 113. In an example, the slotted
region 115 defines about fourteen slots 113.
In an example, the slotted region 115 defines about sixteen slots
113. In an example, the slotted region 115 defines about twelve
slots 113. In other implementations, the slotted region 115 can
define any desired number of slots 113.
As shown in FIG. 8, the slotted region 115 of the tube body 111 has
a length L2 that is generally shorter than the length L1 of the
tube body 111. In some implementations, the length L2 of the axial
region 115 is shorter than the length L1 of the tube body 111. In
certain implementations, the length L2 extends along a majority of
the length L1. In certain implementations, the length L2 is at
least half of the length L1. In certain implementations, the length
L2 is at least 60% of the length L1. In certain implementations,
the length L2 is at least 70% of the length L1. In certain
implementations, the length L2 is at least 75% of the length L1. In
some implementations, each slot 113 extends the entire length L2 of
the axial region 115. In other implementations, each slot 113
extends along a portion of the axial region 115.
In some implementations, a ratio of the length L2 of the slotted
region 115 to a tube diameter D (FIG. 9) is about 1 to about 3. In
certain implementations, the ratio of the length L2 of the slotted
region 115 to the tube diameter D is about 1.5 to about 2. In
certain examples, the ratio of the length L2 of the slotted region
115 to the tube diameter D is about 1.75. In certain examples, the
tube diameter D is about 5 inches and the length L2 of the slotted
region 115 is about 8 inches. In an example, each slot 113 of the
slotted region 115 extends the length L2 of the slotted region
115.
As shown in FIG. 9, the slotted region 115 of the tube body 111 has
a circumferential width S1 that is larger than a circumferential
width S2 of a non-slotted region 116 of the tube body 111. The
non-slotted region 116 defines a circumferential surface of the
tube body 111 through which no slots are defined. In an example,
the non-slotted region 116 defines a solid circumferential surface
through which no openings are defined.
In some implementations, the circumferential width S2 of the
non-slotted region 116 is significantly larger than a
circumferential width of any portion of the tube body 111 extending
between two adjacent slots 113 at the slotted region 115. For
example, in certain examples, the circumferential width S2 of the
non-slotted region 116 is at least double the circumferential width
of any portion of the tube body 111 extending between two adjacent
slots 113 at the slotted region 115. In certain examples, the
circumferential width S2 of the non-slotted region 116 is at least
triple the circumferential width of any portion of the tube body
111 extending between two adjacent slots 113 at the slotted region
115. In certain examples, the circumferential width S2 of the
non-slotted region 116 is at least four times the circumferential
width of any portion of the tube body 111 extending between two
adjacent slots 113 at the slotted region 115. In certain examples,
the circumferential width S2 of the non-slotted region 116 is at
least five times the circumferential width of any portion of the
tube body 111 extending between two adjacent slots 113 at the
slotted region 115.
In some implementations, the circumferential width S1 of the
slotted region 115 is substantially larger than the circumferential
width S2 of the non-slotted region 116. In certain implementations,
the circumferential width S1 of the slotted region 115 is at least
twice the circumferential width S2 of the non-slotted region 116.
In certain implementations, the circumferential width S1 of the
slotted region 115 is about triple the circumferential width S2 of
the non-slotted region 116.
In some examples, the slotted region 115 extends about 200.degree.
to about 350.degree. around the tube body 111 and the non-slotted
region 116 extends about 10.degree. to about 160.degree. around the
tube body 111. In certain examples, the slotted region 115 extends
about 210.degree. to about 330.degree. around the tube body 111 and
the non-slotted region 116 extends about 30.degree. to about
150.degree. around the tube body 111. In an example, the slotted
region 115 extends about 270.degree. around the tube body 111 and
the non-slotted region 116 extends about 90.degree. around the tube
body 111. In an example, the slotted region 115 extends about
300.degree. around the tube body 111 and the non-slotted region 116
extends about 60.degree. around the tube body 111. In an example,
the slotted region 115 extends about 240.degree. around the tube
body 111 and the non-slotted region 116 extends about 120.degree.
around the tube body 111.
In some implementations, each slot 113 has a common width S3
(defined along the circumference of the tube body 111. In some
implementations, the width S3 of each slot 113 is less than the
circumferential width S2 of the non-slotted region 116. In certain
implementations, the width S3 of each slot 113 is substantially
less than the width S2 of the non-slotted region 116. In certain
implementations, the width S3 of each slot 113 is less than half
the width S2 of the non-slotted region 116. In certain
implementations, the width S3 of each slot 113 is less than a third
of the width S2 of the non-slotted region 116. In certain
implementations, the width S3 of each slot 113 is less than a
quarter of the width S2 of the non-slotted region 116. In certain
implementations, the width S3 of each slot 113 is less than 20% the
width S2 of the non-slotted region 116. In certain implementations,
the width S3 of each slot 113 is less than 10% the width S2 of the
non-slotted region 116.
In some implementations, the tube body 111 has a ratio of slot
width S3 to tube diameter D (FIG. 9) of about 0.02 to about 0.2. In
certain implementations, the ratio of slot width S3 to tube
diameter D is about 0.05 to about 0.15. In certain implementations,
the ratio of slot width S3 to tube diameter D is about 0.08 to
about 0.12. In an example, the ratio of slot width S3 to tube
diameter D is about 0.1. In certain examples, the slot width S3 is
about 0.45 inches and the tube diameter D is about 5 inches. In
other implementations, however, the slots 113 can have different
widths.
In some implementations, the slots 113 are spaced evenly around the
circumferential width S1 of the slotted region 115. In such
implementations, gaps between adjacent slots 113 within the slotted
region 115 have a circumferential width S4. In certain
implementations, the circumferential width S4 of the gaps is larger
than the circumferential width S3 of the slots 113. In certain
implementations, the circumferential width S3 of the slots 113 is
at least half of the circumferential width S4 of the gaps. In
certain implementations, the circumferential width S3 of the slots
113 is at least 60% of the circumferential width S4 of the gaps. In
certain implementations, the circumferential width S3 of the slots
113 is at least 75% of the circumferential width S4 of the gaps. In
certain implementations, the circumferential width S3 of the slots
113 is at least 85% of the circumferential width S4 of the gaps. In
other implementations, however, the gaps between the slots 113 can
have different widths.
In some implementations, the width S4 of each gap is less than the
circumferential width S2 of the non-slotted region 116. In certain
implementations, the width S4 of each gap is substantially less
than the width S2 of the non-slotted region 116. In certain
implementations, the width S4 of each gap is less than half the
width S2 of the non-slotted region 116. In certain implementations,
the width S4 of each gap is less than a third of the width S2 of
the non-slotted region 116. In certain implementations, the width
S4 of each gap is less than a quarter of the width S2 of the
non-slotted region 116. In certain implementations, the width S4 of
each gap is less than 20% the width S2 of the non-slotted region
116. In certain implementations, the width S4 of each gap is less
than 10% the width S2 of the non-slotted region 116.
In certain implementations, the slots 113 occupy about 25% to about
60% of the area of the slotted region 115. In certain
implementations, the slots 113 occupy about 35% to about 55% of the
area of the slotted region 115. In certain implementations, the
slots 113 occupy less than about 50% of the area of the slotted
region 115. In certain implementations, the slots 113 occupy about
45% of the area of the slotted region 115. In other words, the
percentage of open area to closed area at the slotted region 115 is
about 45%.
In some implementations, louvers 114 are disposed at the slotted
region 115. In some implementations, each slot 113 has a
corresponding louver 114. In other implementations, however, only a
portion of the slots 113 have a corresponding louver 114. In some
implementations, each louver 114 extends the length of the
corresponding slot 113. In other implementations, a louver 114 can
be longer or shorter than the corresponding slot 113.
As shown in FIG. 9, each louver 114 extends from a base 118 to a
distal end 119 spaced from the tube body 111. In some
implementations, the base 118 is coupled to the tube body 111. In
other implementations, however, the base 118 can be spaced from the
tube body 111 (e.g., suspended adjacent the tube body 111). In some
implementations, the base 118 of each louver 114 is disposed at one
end of a slot 113 so that the louver 114 extends at least partially
over the slot 113 (e.g., see FIG. 9). In certain implementations,
the louver 114 is sized to extend fully across the width S3 of the
slot 113. In other implementations, the louver 114 extends only
partially across the width S3 of the slot 113. In some
implementations, the distal ends 119 of adjacent louvers 114 define
gaps having a circumferential width S5. In certain implementations,
the circumferential width S5 of the gaps is about equal to the
circumferential width S3 of the slots 113 and the circumferential
width S4 of the gaps.
In some implementations, each louver 114 extends straight from the
slot 113 to define a plane. In certain implementations, the louvers
114 extend from the slot 113 at an angle .theta. relative to the
tube body 111. In certain implementations, the angle .theta. is
about 20.degree. to about 70.degree.. In an example, the angle
.theta. is about 45.degree.. In an example, the angle .theta. is
about 40.degree.. In an example, the angle .theta. is about
50.degree.. In an example, the angle .theta. is about 35.degree..
In certain implementations, the angle .theta. is about 30.degree.
to about 55.degree.. In other implementations, each louver 114
defines a concave curve as the louver 114 extends away from the
slot 113.
In some implementations, the tube body 111 has a louvered region
over which the louvers 114 extend and a non-louvered region over
which no louver extends. In some such implementations, the louvered
region extends about 200.degree. to about 350.degree. around the
tube body 111 and the non-louvered region extends about 10.degree.
to about 160.degree. around the tube body 111. In certain examples,
the louvered region extends about 210.degree. to about 330.degree.
around the tube body 111 and the non-louvered region extends about
30.degree. to about 150.degree. around the tube body 111. In an
example, the louvered region extends about 270.degree. around the
tube body 111 and the non-louvered region extends about 90.degree.
around the tube body 111. In certain examples, the louvered region
largely corresponds with the slotted region 115. In an example, the
louvered region overlaps the slotted region 115.
Various modifications and alterations of this disclosure will
become apparent to those skilled in the art without departing from
the scope and spirit of this disclosure, and it should be
understood that the scope of this disclosure is not to be unduly
limited to the illustrative embodiments set forth herein.
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